Fused Heteroaromatic Organic Compounds for High‐Power Electrodes of Rechargeable Lithium Batteries

Organic redox compounds are emerging electrode materials for rechargeable lithium batteries. However, their electrically insulating nature plagues efficient charge transport within the electroactive bulk. Alternative to the popular solution of elaborating nanocomposite materials, herein we report on a molecular‐level engineering strategy towards high‐power organic electrode materials with multi‐electron reactions. Systematic comparisons of anthraquinone analogues incorporating fused heteroaromatic structures as cathode materials in rechargeable lithium batteries reveal that the judicious incorporation of heteroaromatics improves the cell performance in terms of specific gravimetric capacity, working potential, rate capability, and cyclability. Combination studies with morphological observation, electrochemical impedance characterization, and theoretical modeling provide insight into the advantage of heteroaromatic building blocks. In particular, benzofuro[5,6‐b]furan‐4,8‐dione ( BFFD ) bearing furan moeities shows a reversible capacity of 181 mAh g^?1 when charged/discharged at 100C, corresponding to a power density of 29.8 kW kg^?1. These results have pointed to a general design route of high‐rate organic electrode materials by rational functionalization of redox compounds with appropriate heteroaromatic units as versatile structural tools.     

Electrochemical Performance of Porous Carbon/Tin Composite Anodes for Sodium‐Ion and Lithium‐Ion Batteries

The electrochemical performance of mesoporous carbon (C)/tin (Sn) anodes in Na‐ion and Li‐ion batteries is systematically investigated. The mesoporous C/Sn anodes in a Na‐ion battery shows similar cycling stability but lower capacity and poorer rate capability than that in a Li‐ion battery. The desodiation potentials of Sn anodes are approximately 0.21 V lower than delithiation potentials. The low capacity and poor rate capability of C/Sn anode in Na‐ion batteries is mainly due to the large Na‐ion size, resulting in slow Na‐ion diffusion and large volume change of porous C/Sn composite anode during alloy/dealloy reactions. Understanding of the reaction mechanism between Sn and Na ions will provide insight towards exploring and designing new alloy‐based anode materials for Na‐ion batteries.     

酰基供体结构对褶皱念珠茵脂肪酶（CRL）催化芳香仲醇动力学拆分立体选择性的影响

研究仲醇的酶催化动力学拆分机制,发现酰基供体的结构是影响酶催化动力学拆分选择性的一个重要因素。通过实验发现了一类用于仲醇动力学拆分（KR）的优秀酰基供体——长链有机酸的对氯苯酚酯,并将这种酰基供体成功用于褶皱念珠菌脂肪酶（CRL）催化的仲醇动力学拆分过程。在1-苯乙醇的动力学拆分（KR）过程中,随着对氯苯酚有机酸酯供体中酰基部分碳原子数的增加,产物的对映体过量值（e．e.p值）也在不断地提高。当碳原子数≥5,转化率达到50％时,产物的叫．。值仍能保持大于99％。这样的规律也适用于其他的仲醇拆分过程,当选择对氯苯酚戊酸酯作为酰基供体用于其他仲醇的动力学拆分过程时,可以实现仲醇的高效拆分,反应6h转化率达到50％,产物的对映体过量值e．e．p为100％。     

Expression patterns and adaptive functional diversity of vertebrate myoglobins

Recent years have witnessed a new round of research on one of the most studied proteins - myoglobin (Mb), the oxygen (O₂) carrier of skeletal and heart muscle. Two major discoveries have stimulated research in this field: 1) that Mb has additional protecting functions, such as the regulation of in vivo levels of the signaling molecule nitric oxide (NO) by scavenging and generating NO during normoxia and hypoxia, respectively; and 2) that Mb in vertebrates (particularly fish) is expressed as tissue-specific isoforms in other tissues than heart and skeletal muscle, such as vessel endothelium, liver and brain, as found in cyprinid fish. Furthermore, Mb has also been found to protect against oxidative stress after hypoxia and reoxygenation and to undergo allosteric, O₂-linked S-nitrosation, as in rainbow trout. Overall, the emerging evidence, particularly from fish species, indicates that Mb fulfills a broader array of physiological functions in a wider range of different tissues than hitherto appreciated. This new knowledge helps to better understand how variations in Mb structure and function may correlate with differences in animals' lifestyles and hypoxia-tolerance. This review integrates old and new results on Mb expression patterns and functional properties amongst vertebrates and discusses how these may relate to adaptive variations in different species. This article is part of a special issue entitled: Oxygen Binding and Sensing Proteins.     

Recombination in Polymer:Fullerene Solar Cells with Open‐Circuit Voltages Approaching and Exceeding 1.0 V

Polymer:fullerene solar cells are demonstrated with power conversion efficiencies over 7% with blends of PBDTTPD and PC₆₁BM. These devices achieve open‐circuit voltages (V_oc) of 0.945 V and internal quantum efficiencies of 88%, making them an ideal candidate for the large bandgap junction in tandem solar cells. V_oc’s above 1.0 V are obtained when the polymer is blended with multiadduct fullerenes; however, the photocurrent and fill factor are greatly reduced. In PBDTTPD blends with multiadduct fullerene ICBA, fullerene emission is observed in the photoluminescence and electroluminescence spectra, indicating that excitons are recombining on ICBA. Voltage‐dependent, steady state and time‐resolved photoluminescence measurements indicate that energy transfer occurs from PBDTTPD to ICBA and that back hole transfer from ICBA to PBDTTPD is inefficient. By analyzing the absorption and emission spectra from fullerene and charge transfer excitons, we estimate a driving free energy of –0.14 ± 0.06 eV is required for efficient hole transfer. These results suggest that the driving force for hole transfer may be too small for efficient current generation in polymer:fullerene solar cells with V_oc values above 1.0 V and that non‐fullerene acceptor materials with large optical gaps (>1.7 eV) may be required to achieve both near unity internal quantum efficiencies and values of V_oc exceeding 1.0 V.     

Si‐Encapsulating Hollow Carbon Electrodes via Electroless Etching for Lithium‐Ion Batteries

Remarkable improvements in the electrochemical performance of Si materials for Li‐ion batteries have been recently achieved, but the inherent volume change of Si still induces electrode expansion and external cell deformation. Here, the void structure in Si‐encapsulating hollow carbons is optimized in order to minimize the volume expansion of Si‐based anodes and improve electrochemical performance. When compared to chemical etching, the hollow structure is achieved via electroless etching is more advanced due to the improved electrical contact between carbon and Si. Despite the very thick electrodes (30 ～ 40 μm), this results in better cycle and rate performances including little capacity fading over 50 cycles and 1100 mA h g^?1 at 2C rate. Also, an in situ dilatometer technique is used to perform a comprehensive study of electrode thickness change, and Si‐encapsulating hollow carbon mitigates the volume change of electrodes by adoption of void space, resulting in a small volume increase of 18% after full lithiation corresponding with a reversible capacity of about 2000 mA h g^?1.     

铜胁迫条件下土壤微生物对海州香薷光合特性和叶绿素荧光参数的影响

为探讨铜（Cu）胁迫条件下土壤微生物对海州香薷（Elsholtzia splendens）光合生理和叶绿素荧光参数的影响,实验设置添加Cu（Cu胁迫）、接种土壤微生物、添加Cu与接种土壤微生物等3个处理,以不添加Cu与不接种土壤微生物为对照（CK）。结果表明：接种土壤微生物处理的植株相对叶绿素含量、净光合速率（P_n）、水分利用效率（WUE）均显著高于CK;且对初始荧光（F_o）和最大光化学效率（F_v/F_m）均有显著性影响。与CK相比,添加Cu降低了海州香薷的P_n和气孔导度（G_s）,但胞间CO₂浓度（C_i）的变化与P_n相反,表明其对光合作用的影响主要是非气孔限制因素。添加Cu的植株相对叶绿素含量显著下降,但Cu胁迫下接种土壤微生物提高了植株相对叶绿素含量,差异显著。在Cu胁迫条件下,接种土壤微生物的植株具有较高的F_v/F_m及较低的F_o,显著提高了海州香薷的WUE、P_n、G_s。说明接种土壤微生物可通过提高相对叶绿素含量、改善叶绿素荧光和光合作用来减轻Cu胁迫对海州香薷植株造成的伤害,从而提高海州香薷耐受Cu胁迫的能力。     

钢渣组分特征及其用于土壤改良的可行性初步研究

通过测定钢渣的化学组成分析得出其组分特征,进一步通过在有降解碱剂HPMA参与的重（轻）度盐碱土壤及钢渣中栽种不同植物种子（玉米、茄子、水稻和长春花）,观察植物的长势,探究钢渣是否可以用于土壤改良。结果发现钢渣的化学成分与土壤基本相同,但部分成分如CaO、Fe₂O₃、MgO、MnO₂等显著高于土壤,而另外一些组分TiO₂、K₂O、Na₂O、P₂O₅在钢渣中未检测出来。对比重（轻）度盐碱土壤,钢渣与HPMA共同作用时,玉米、茄子、水稻和长春花等发芽率及生长速率明显提高;与常用的蛭石、珍珠岩改良剂对比实验中,不同植物存在类似的发芽率和生长速率,说明钢渣可以作为温室土壤结构改良剂;与钢渣产地丰富的树皮土资源配比形成复方改良剂,发现其具有类似花土（泥炭土）的生长速率和发芽率。初步研究表明,钢渣可以用于盐碱地改良,而且对于设施农业的土壤结构改良具有功效,与当地树皮土资源结合,具有形成复方土壤改良剂的潜力。     

Long-term tillage effects on soil organic carbon and dissolved organic carbon in a purple paddy soil of Southwest China

The impact of conservation tillage practices on soil carbon has been of great interest in recent years. Conservation tillage might have the potential to enhance soil carbon accumulation and alter the depth distribution of soil carbon compared to conventional tillage based systems. Changes in the soil organic carbon (SOC) as influenced by tillage, are more noticeable under long-term rather than short-term tillage practices. The objective of this study was to determine the impacts of long-term tillage on SOC and dissolved organic carbon (DOC) status after 19 years of four tillage treatments in a Hydragric Anthrosol. In this experiment four tillage systems included conventional tillage with rotation of rice and winter fallow system (CTF), conventional tillage with rotation of rice and rape system (CTR), no-till and ridge culture with rotation of rice and rape system (NT) and tillage and ridge culture with rotation of rice and rape system (TR). Soils were sampled in the spring of 2009 and sectioned into 0–10, 10–20, 20–30, 30–40, 40–50 and 50–60 cm depth, respectively.Tillage effect on SOC was observed, and SOC concentrations were much larger under NT than the other three tillage methods in all soil depths from 0 to 60 cm. The mean SOC concentration at 0–60 cm soil depth followed the sequence: NT (22.74 g kg^?1) > CTF (14.57 g kg^?1) > TR (13.10 g kg^?1) > CTR (11.92 g kg^?1). SOC concentrations under NT were significantly higher than TR and CTR (P < 0.01), and higher than CTF treatment (P < 0.05). The SOC storage was calculated on equivalent soil mass basis. Results showed that the highest SOC storage at 0–60 cm depth presented in NT, which was 158.52 Mg C ha^?1, followed by CTF (106.74 Mg C ha^?1), TR (93.11 Mg C ha^?1) and CTR (88.60 Mg C ha^?1). Compared with conventional tillage (CTF), the total SOC storage in NT increased by 48.51%, but decreased by 16.99% and 12.77% under CTR and TR treatments, respectively. The effect of tillage on DOC was significant at 0–10 cm soil layer, and DOC concentration was much higher under CTF than the other three treatments (P < 0.01). Throughout 0–60 cm soil depth, DOC concentrations were 32.92, 32.63, 26.79 and 22.10 mg kg^?1 under NT, CTF, CTR and TR, and the differences among the four treatments were not significant (P > 0.05). In conclusion, NT increased SOC concentration and storage compared to conventional tillage operation but not for DOC.